Fellow 40+ men - how many push-ups can you complete in a single set?

Since the beginning of the year I've been trying to build my upper body strength a bit. I could previously only do 10-12 push ups but now can consistently do 18 to 20 - it still feels pretty measly. I've never been particularly strong, I'm built more for speed. 150lbs/68kg.

Edit to add: Thanks everyone for the responses - my takeaway is that I could probably do with raising the bar a bit. Thanks to those who offered advice and encouragement, I'll try and take the motivation and sustain it for as long as possible!