Driving the lexus ls 400 less and less

I'm working from home for about a month now, which means less and less driving the Lexus.

Mileage on odometer: 
155,563.00
Miles driven: 
344
Fuel added: 
18.97
Fuel type: 
87
Cost: 
51.96
Calculated Mileage: 
18.1339

Mileage for this trip:

18.13 miles per gallon.