How rare is the blue card (in monkey knowledge pack)?

Bounty Cards were added in v150831, which was released on August 31st, 2015. There are 10 (11 in mobile) different rewards possible, all with the same chance appearing:

• 1 Ancient Knowledge Pack
• 2 Wild Pack
• 4 Monkey Knowledge Pack
• 1 of each Boss Ability
• 5 Supply crate
• 5 Monkey boost
• 10 Red hot spikes
• 20000 City cash
• 5 Bonus Monkeys (mobile only)
• 30 Bloonstones (Minimum City Level 15)
• 1 Monkey Secret - Gives 250 points all books (Minimum City Level 15)

Thus, the probability of getting the Monkey Secret is 1/11 = 9.1%

It would be a 9.1% chance in mobile, where there is eleven possible rewards from bounty. On the web version, there would be ten possibilities, therefore the probability of obtaining the Monkey Secret would be 10% from bounty cards, and therefore 1% from a regular pack.