select date_trunc('day', hour) as date, avg(price) as price

from ethereum.core.fact_hourly_token_prices

where date >= '2021-01-01' and symbol = 'stETH'

group by 1

),

eth as (

select date_trunc('day', hour) as date, avg(price) as price

from ethereum.core.fact_hourly_token_prices

where date >= '2021-01-01' and symbol = 'WETH'

group by 1

select avg (eth.price - steth.price)

from steth, eth