65% of them work in construction, which is the highest paying category of work.
This chart shows the comparative daily wages in shekels for Palestinians in the West Bank, Gaza and Israel/settlements for different types of jobs.
While some 13% of Palestinians work for Israelis, based on the averages in the chart above, it appears that about half of all Palestinian construction workers are actually working in Israeli communities and a much smaller percentage of the other categories.
Last year several thousand Gazans were quietly allowed to work in southern Israel. I do not believe that the PCBS has those people included; Hamas probably has those statistics.
Also, there are many Palestinian workers who depend on business from Israel but who are not employees. I know that some Israeli high-tech firms outsource programming to Palestinian consultants, for example. If Palestinians would succumb to BDS-style pressure, their economy would be devastated.
(h/t Ibn Boutros)