Question: What percentage of upper middle income countries which have the CO2 emissions from liquid fuel consumption (% of total)

less than 80%?
SQL: SELECT SUM(CASE WHEN T2.IndicatorName = 'CO2 emissions FROM liquid fuel consumption (% of total)' AND t2.Value < 80 THEN 1 ELSE 0 END) * 1.0 / COUNT(T1.CountryCode) persent FROM Country AS T1 INNER JOIN Indicators AS T2 ON T1.CountryCode = T2.CountryCode WHERE T1.IncomeGroup = 'Upper middle income'