According to this article - which was used as the source for the Wikipedia chart:
Demographic Trends in Israel and Palestine by Sergio Dellapergola
Population distribution by main ethnoreligious groups shows an uninterrupted presence of Jews, and subsequently Christians
and Muslims, over most of the last two millennia, along with significant changes over time in the absolute and relative size of these
groups. Archaeological and documentary evidence points to the early prevalence of Jewish population, political organization, and
culture. Then, between the fourth and seventh centuries—the Byzantine period—the majority of the population was Christian.
With the rise of Islam after the seventh century, a Muslim majority emerged. This lasted through 1947, when, out of an estimated
total population of about 2 million, close to 1.2 million (60 percent) were Muslims, about 650,000 (32 percent) Jews, and about
150,000 (7 percent) Christians.12
Following Israel's 1948 War of Independence and the farreaching political changes that came in its wake, a Jewish majority
emerged again in the whole territory of historic Palestine. One of the determinants of this shift was the flight from Palestine
of 625,000-675,000 Arabs, according to Israeli sources,13 or 700,000-850,000, according to Palestinian sources.14 These have
been recognized, together with their descendants, as the Palestinian refugees.15 Another key determinant of population change beginning
with Israeli independence was large-scale, unrestricted Jewish immigration, which amounted to 2,850,000 between 1948
and 2000. Differential natural increase of the main ethnoreligious groups further contributed to the changes in population size and
composition.
From page 19, he talks about Arab immigration into Israel for jobs:
The consequence for Israel was that an Arab labor force becameone of the essential prerequisites for the construction of a modern
Jewish state. And as far as the Palestinians were concerned, were it not for the existence of the State of Israel, a large share of
the Palestinian labor force, unable to find employment locally, would have been forced to migrate elsewhere in search of work. Indeed,
about 140,000 Palestinians emigrated from the West Bank during the 1960s—ruled, at the time by Jordan—looking for jobs.
Afterwards, from the 1967 Israeli occupation until 1989, 171,000 Palestinians left the West Bank and 114,000 the Gaza area in search
of the new opportunities opening up in the booming economies of the Gulf States. After the 1991 Gulf War, about 30,000 returned,
and another 30,000—mostly people related to members of the Palestinian Authority's administration and military forces—came
back to Palestine after the Oslo agreements.27
Part of the problem with historic population analysis though is that data can be very unreliable since it's not based on modern methodology. From:
MidEast Web - Population of Palestine
Economics and Immigration - Under the British Mandate, which began after WWI, Jewish population increased due to immigration, especially in the 1930s. Arab population also increased at an exceptional rate. According to records, about 18,000 non-Jews entered Palestine between 1930 and 1939 when there were more or less reliable figures. In the same period, about 5,000 non-Jews left. This does not count illegal immigration of course, or immigration prior to 1930. Economic analyses show that by the 1930s the standard of living of Palestinian Arabs was approximately twice that of Arabs in surrounding countries, whereas in Ottoman Turkish times it was lower than in surrounding countries. Some of the farm population may have suffered economic hardship, characteristic of any industrializing and urbanizing society, but in the main, the standard of living improved, and it improved much faster than it did in surrounding countries. There is no doubt that this improvement in conditions was an attractant for immigrants as well as resulting in improved health and larger families. Additionally, British activity in building the port of Haifa during the 1920s and in operating it during WW II undoubtedly attracted at least some immigrants. However, there is no hard evidence that more than 100,000 or 200,000 (out of about 1.3 million in all of Palestine, and about 7-800,000 in the area that was to become Israel in 1948) Palestinians had immigrated to the land that was to become Israel. It is impossible to determine at present when this immigration took place. 100,000 Arabs immigrating in 1880 would have produced many more descendants by 1948 than 100,000 Arabs immigrating in 1930. However, since economic conditions did not improve until mandatory times, it is unlikely that the bulk of the immigration occurred under Turkish administration.
This author also makes the following conclusions: Palestine was not an empty land when Zionist immigration began (estimates range from 410,000 to over 600,000 Arab Muslims and Christians in the 1890's); Zionist settlement did not displace or dispossess Palestinians and while it's not possible to estimate illegal Arab immigration directly, there was some.
