| From | To | Rate |
| 01 April 1973 | 28 July 1974 | 10% |
| 29 July 1974 | 17 June 1979 | 8% |
| 18 June 1979 | 31 March 1991 | 15% |
| 01 April 1991 | 30 November 2008 | 17.5% |
| 01 December 2008 | 31 December 2009 | 15% |
| 01 January 2010 | 03 January 2011 | 17.5% |
| 04 January 2011 | Current | 20% |
| From | To | Rate |
| 01 April 1973 | 28 July 1974 | 10% |
| 29 July 1974 | 17 June 1979 | 8% |
| 18 June 1979 | 31 March 1991 | 15% |
| 01 April 1991 | 30 November 2008 | 17.5% |
| 01 December 2008 | 31 December 2009 | 15% |
| 01 January 2010 | 03 January 2011 | 17.5% |
| 04 January 2011 | Current | 20% |