He currently boasts 148,000 followers and uses Instagram far more than the NDP's previous leader Tom Mulcair who only has 8,376 followers..."
Number of followers is not the same as usage. Someone could theoretically post only one photo, but still have thousands of followers.
Singh has posted more than Angus or Mulcair: 618 photos. 149K followers. (241 per photo)
Angus is second, posting-wise: 239 photos. 574 followers (2.4 per photo)
Mulcair, last, posting-wise: 183 photos. 8361 followers (45.5 per photo)