N purchased a home in Toronto in Year 1. N was transferred by his employer from Toronto to Vancouver in Year 3. N was transferred back to his employer's Toronto office and moved back into his Toronto home in Year 9. N sold his Toronto home in Year 15. During Years 3 to 9 the Toronto home was rented to a young couple through a rental agency. For how many of the Years 1 through 9 does the Toronto home qualify to be designated as a principal residence, assuming an election was made with N's tax return for Year 2 not to recognize the change of use?