Complex sentence: The sum of the prior SLS program funding from 2011 to 2015, funding enacted for 2016, funding planned for 2017 through 2021, and funding through completion of development by 2023 is $20.0 billion (nominal).
Split into simpler sentences: The sum of the prior SLS program funding from 2011 to 2015, funding enacted for 2016. Funding planned for 2017 through 2021, and funding through completion of development by 2023 is $20.0 billion (nominal).