That's the rules. All a club is required to offer as a minimum, is 5%..
Article 38 Ticketing
38.01 Home clubs must make at least 5% of the total approved UEFA capacity of their stadium available exclusively to visiting supporters, in a segregated, safe area. In addition, visiting clubs are entitled to purchase 200 top-category tickets for their VIP supporters, sponsors, etc., but they are not obliged to take the full allocation (see Articles 16 and 23 of the UEFA Stadium Infrastructure Regulations and Article 19 of the UEFA Safety and Security Regulations).
I gathered that was the rule, I just thought that there would be 10%, just my expectation. I bet we give them more...