Its testing that determines the infection rate, the more you test the more you find, the Uk is testing give or take 100'000 a day and report 4'000 cases a day which suggests a 4% infection rate, however you can't extrapolate that across the whole population because they are only testing selected groups, most of whom are at higher risk, there is a random sample being undertaken that should better inform population infection rates, but this will only pick up currently infected not people who have been infected.
It seems from early reports that most countries that have eased the lockdown have seen the rate tick up again with one chap in Seoul visiting 5 night clubs leading to 40 plus infections, fortunately their trace and track systems are well in advance of most western countries, but they now closed 2000 or was it 20000 night clubs !!
I suspect that Spain will see a second surge within 14 days, the distancing rules are being flouted and many are back to kissing and hugging anyone they meet. The only response should this happen is a further bout of restrictions which would spell game over for tourism this year.