New Delhi, June 15 -- Almost one in three persons tested for the coronavirus disease (Covid-19) in Delhi this week had the infection, according to government data. The average positivity rate - the percentage of people who test positive - in Delhi during the week was 30.5% , a number that is perhaps as indicative of the inherent bias in testing (which has only become more marked, especially in Delhi) as it is of the spread of the pandemic in the capital. The national average positivity rate is around 7%, according to the Indian Council of Medical Research (ICMR)....