PA claim 9-fold population increase since "Nakba"
“The [Palestinian] Central Bureau of Statistics (PCBS) said in its latest report last year  on Nakba Day that the number of Palestinians has increased ninefold since the Nakba (i.e., “the catastrophe,” Palestinian term for the establishment of the State of Israel) and at the end of 2018 had reached approximately 13.1 million people, including 6.02 million refugees…
It also noted that the [PA] governmental statistics for 2017 showed that the Palestinian refugees constitute 43% of all the Palestinian residents living in the State of Palestine.”
Nakba Day - Palestinians commemorate Nakba Day on May 15, the day after the establishment of Israel. On May 15, 1948, combined forces from Egypt, Jordan, Syria and Iraq joined local Arab forces in an attempt to eradicate the newly established State of Israel. The Nakba (Arabic = catastrophe) refers to the establishment of Israel, and the subsequent defeat in the war, including the killing and displacement of Arab civilians that occurred during the war.