Repeat the last value over time

Question

I have a table with power plant capacities in different years. There are only entries when something changes in the capacities. In the years not listed, the last value applies.

Plant	Year	Capacity
Cottam	2003	800
Cottam	2009	600
Cottam	2015	800
Drax	2000	600
Drax	2005	1200
Drax	2010	1800
Drax	2013	1200
Drax	2020	0
Ironbridge	2007	500
Ironbridge	2015	0

Now I would like to transform the initial table, so that I also have values for all years in between and can display them in a stacked column chart, for example. The result should look like shown in the table below. Marked in yellow are the numbers from the initial table.

Answer 1

Here's how to solve this (more easily) in DAX:

1. Prerequisite is separate Calendar table with a 1:many relation on the year

Calendar = 
SELECTCOLUMNS(
   GENERATESERIES(
       MIN(Plants[Year]),
       MAX(Plants[Year])
   ),
   "Year", [Value]
)

2. Next calculate the Last Given Capacity per year

Last Given Capacity = 
VAR current_year = 
    MAX(Calendar[Year])
VAR last_capacity_year =
    CALCULATE(
        MAX(Plants[Year]),
        'Calendar'[Year] <= current_year
    )
RETURN
    CALCULATE(
        MAX(Plants[Capacity]),
        Calendar[Year] = last_capacity_year
    )

3. Finally put it all together in a Stacked Column Chart with

X-axis: 'Calendar'[Year]
Y-axis: [Last Given Capacity]
Legend: 'Plants'[Plant]