You have the <strong> tag around each of the years but have you noticed that they aren’t bold? Try removing your call to the ‘Sniglet’ font and you’ll see the difference.
The reason this is happening is because when you set the link to Sniglet you only set it to the default weight of 400. Go back to Google Fonts and when you select your font it will give you the link. All well and good so far but what you then need to do is click on the ‘customize’ link (next to ‘embed’) and there click the extra bold checkbox. Click the ‘embed’ link and put the new link in your page. (Notice it now has weights for 400 & 800)
So it looks like the font you choose only has a normal weight and a bold weight. There are others that support different weights and italics. (For grins, look at ‘Roboto’.)
Btw, I did this too with a page I was working on and asked a question about why I wasn’t seeing the font output the way I expected here in the forums and it was explained to me. Here’s the link to my post which includes a quick video the responder made showing how to do what I just explained.