Yeah, your cadence is not bad at all. The quick answer is high. Higher the better. IMO cadence also changes with fitness. I can climb at higher (than normal) cadence with higher wattage on long climbs when I'm fit. My fitness drops so does my cadence. 30+ in the back helps. A good cardiovascular system immensely helps. I have been working on my cadence past few years. It's not easy to be quite honest. Going from 90 to 92 rpm is not easy. Gains have been very gradual. It seems like there's an optimum cadence that suits your fitness, body composition, gradient etc. All bets are off when the gradient goes around/over mid-teen percentages. 60-65 sounds about right. I have a buddy who lived in Barcelona for a while and he was talking about these climbs the other day. I was like wow you are serious this is awesome. Also was watching 2009 TdF stage 6 where the stage ended in Barcelona a week ago on the trainer. Pretty bad David Millar couldn't make it into the finish line but was super fun to watch the peloton rolling thru the wide streets of the city.