On 26 August 1643, during the minority of the former chief, "the Estates of the Kingdom passed an Act for the Committees of War in the shires of Scotland", and among the Commissioners for the Sheriffdom of Sutherland and a par of Inverness-shire, occurs the name of "Sir Robert Munro, tutour of Foulles"; and again on 24 July 1644, in a commission for a similar purpose and for the same Sheriffdom is found the name of "Sir Robert Monro, Tutor of Foullis". In 1649, the Scottish Parliament separated from the Sherriffdom of Inverness-shire the "lands eastward of Altnalait, Knockravock and the Royal Burgh of Tain", erected the Sherriffdom of Ross, and appointed the Marquiss of Argyll the Sherriff-Principal. Afterwards the commission was granted to Sir Robert Munro, who had been elected Member of Parliament for Inverness-shire in 1649 and for his own County of Ross after it was separated from the County of Inverness, 1649-50, to be Sheriff-Principal of the County of Ross. In 1651 Robert succeeded to the head of his house, upon the death of his cousin Sir Hector Munro, 2nd Baronet of Foulis who died at just 17 years of age, as already mentioned. Robert took up his residence in Foulis Castle.

Based on the above article, answer a question. How many years after Sir Robert Munro was elected Member of Parliament for Inverness-shire did he succeede to the head of his house?
2