What was the change in Computer hardware and software between 2018 and 2019?
{"Land, buildings and improvements": {"2019": 289051, "2018": 267809}, "Machinery and equipment": {"2019": 381656, "2018": 364034}, "Computer hardware and software": {"2019": 136227, "2018": 130645}, "Capital assets in progress": {"2019": 49599, "2018": 38469}, "Total property, plant and equipment, gross ": {"2019": 856533, "2018": 800957}, "Less: accumulated depreciation ": {"2019": -472309, "2018": -459651}, "Total property, plant and equipment, net": {"2019": 384224, "2018": 341306}}
computer_hardware_and_software_2019 = df["Computer hardware and software"]["2019"]
computer_hardware_and_software_2018 = df["Computer hardware and software"]["2018"]
answer = computer_hardware_and_software_2019 - computer_hardware_and_software_2018