property investmentp yrr our overall strategy is to continue to increase our investment in quality industrial properties in both existing and select new markets and to continue to increase our investment in on-campus or hospital affiliated medical offf fice ff properties . pursuant to this strategy , we evaluate development and acquisition opportunities based upon our market yy outlook , including general economic conditions , supply and long-term growth potential . our ability to make future property investments is dependent upon identifying suitable acquisition and development opportunities , and our continued access to our longer-term sources of liquidity , including issuances of debt or equity securities as well asyy generating cash flow by disposing of selected properties . leasing/capital costsg p tenant improvements and lease-related costs pertaining to our initial leasing of newly completed space , or vacant tt space in acquired properties , are referred to as first generation expenditures . such first generation expenditures for tenant improvements are included within "development of real estate investments" in our consolidated statements of cash flows , while such expenditures for lease-related costs are included within "other deferred leasing costs." cash expenditures related to the construction of a building's shell , as well as the associated site improvements , are also included within "development of real estate investments" in our consolidated statements of cash flows . tenant improvements and leasing costs to re-let rental space that we previously leased to tenants are referred to as tt second generation expenditures . building improvements that are not specific to any tenant , but serve to improve integral components of our real estate properties , are also second generation expenditures . one of the principal uses of our liquidity is to fund the second generation leasing/capital expenditures of our real estate investments . the following table summarizes our second generation capital expenditures by type of expenditure , as well as capital expenditures for the development of real estate investments and for other deferred leasing costs ( in thousands ) : .

2016: second generation tenant improvements: 24622
second generation leasing costs: 27029
building improvements: 7698
total second generation capital expenditures: 59349
development of real estate investments: 401442
other deferred leasing costs: 38410
2015: second generation tenant improvements: 28681
second generation leasing costs: 24471
building improvements: 8748
total second generation capital expenditures: 61900
development of real estate investments: 370466
other deferred leasing costs: 30790
2014: second generation tenant improvements: 51699
second generation leasing costs: 37898
building improvements: 9224
total second generation capital expenditures: 98821
development of real estate investments: 446722
other deferred leasing costs: 31503

second generation capital expenditures were significantly lower during 2016 and 2015 , compared to 2014 , as the result of significant dispositions of office properties , which were more capital intensive to re-lease than industrial ff properties . we had wholly owned properties under development with an expected cost of ww $ 713.1 million at december 31 , 2016 , compared to projects with an expected cost of $ 599.8 million and $ 470.2 million at december 31 , 2015 and 2014 , respectively . the capital expenditures in the table above include the capitalization of internal overhead costs . we capitalized ww $ 24.0 million , $ 21.7 million and $ 23.9 million of overhead costs related to leasing activities , including both first and second generation leases , during the years ended december 31 , 2016 , 2015 and 2014 , respectively . we ww capitalized $ 25.9 million , $ 23.8 million and $ 28.8 million of overhead costs related to development activities , including both development and tenant improvement projects on first and second generation space , during the years ended december 31 , 2016 , 2015 and 2014 , respectively . combined overhead costs capitalized to leasing and development totaled 33.5% ( 33.5 % ) , 29.0% ( 29.0 % ) and 31.4% ( 31.4 % ) of our overall pool of overhead costs at december 31 , 2016 , 2015 and 2014 , respectively . further discussion of the capitalization of overhead costs can be found in the year-to-year comparisons of general and administrative expenses and critical accounting policies sections of this item 7. .

Questions:
what were the total costs associated with development and tenant improvement projects on first and second generation space in the year of 2016?
and what were they in 2014?
what is, then, the total value of those costs in 2014 and 2016?
what were the total costs associated with development and tenant improvement projects on first and second generation space in the year of 2015?
what is, then, the total value of those costs, including the year of 2015?

Answers:
25.9
28.8
54.7
23.8
78.5