My ds had maybe 3 tantrums between the ages of 2 & 3 and yet that was when I was expecting them. He had more when he was 3, but not a huge number. He probably had more after he turned 4 & definitely should have known better!
My dd on the other hand is only 14 months old and can already grunt and cry in annoyance with the best of them! You should see her when her big brother has something she wants and she can't get it.
I think the difference is the level of frustration with communication. My ds had 12 words at 12 months that he used regularly, had a bit of a dip in his words for a few months due to ear infections but then had a speech explosion at 16 - 18 months and was speaking long sentences at 18 - 20 months. My dd is nearly 15 months and doesn't use ANY words regularly (well not any words that we understand or in context) and I can see her frustration at her inability to communicate.