I – 1980 -University of Peradeniya
II – 1983 -University of Colombo
III – 1986 -University of Kelaniya
IV – 1992 – University of Sri Jayawardenepura
V – 1995 -University of Moratuwa
VI – 1998 -University of Ruhuna
VII – 2001 -University of Peradeniya
VIII – 2004 -University of Colombo
IX – 2007 -University of Kelaniya
X – 2010 – University of Sri Jayawardenepura
XI – 2013 -University of Moratuwa
XII – 2016 -University of Wayamba