The Presbyterian Church in Taiwan (PCT) is by far the largest Protestant denomination in Taiwan, with some 238,372 members as of 2009 (including a majority of the island's aborigines). English Presbyterian missionary James Laidlaw Maxwell established the first Presbyterian church in Tainan in 1865. His colleague George Leslie Mackay, of the Canadian Presbyterian Mission, was active in Danshui and north Taiwan from 1872 to 1901; he founded the island's first university and hospital, and created a written script for Taiwanese Minnan. The English and Canadian missions joined together as the PCT in 1912. One of the few churches permitted to operate in Taiwan through the era of Japanese rule (1895–1945), the PCT experienced rapid growth during the era of Guomindang-imposed martial law (1949–1987), in part due to its support for democracy, human rights, and Taiwan independence. Former ROC president Lee Teng-hui (in office 1988–2000) is a Presbyterian.

Answer this question, if possible (if impossible, reply "unanswerable"): Since 1988, who has served as the current ROC president?
unanswerable