guidance to amend or clarify portions of the final rule in 2013 . we anticipate that if the epa issues additional responses , amendments and/or policy guidance on the final rule , it will reduce the anticipated capital , operations and maintenance costs resulting from the regulation . generally , the nsps final rule will require expenditures for updated emissions controls , monitoring and record-keeping requirements at affected facilities in the crude-oil and natural gas industry . we do not expect these expenditures will have a material impact on our results of operations , financial position or cash flows . cercla - the federal comprehensive environmental response , compensation and liability act , also commonly known as superfund ( cercla ) , imposes strict , joint and several liability , without regard to fault or the legality of the original act , on certain classes of 201cpersons 201d ( defined under cercla ) that caused and/or contributed to the release of a hazardous substance into the environment . these persons include but are not limited to the owner or operator of a facility where the release occurred and/or companies that disposed or arranged for the disposal of the hazardous substances found at the facility . under cercla , these persons may be liable for the costs of cleaning up the hazardous substances released into the environment , damages to natural resources and the costs of certain health studies . neither we nor oneok partners expect our respective responsibilities under cercla , for this facility and any other , will have a material impact on our respective results of operations , financial position or cash flows . chemical site security - the united states department of homeland security released an interim rule in april 2007 that requires companies to provide reports on sites where certain chemicals , including many hydrocarbon products , are stored . we completed the homeland security assessments , and our facilities subsequently were assigned one of four risk-based tiers ranging from high ( tier 1 ) to low ( tier 4 ) risk , or not tiered at all due to low risk . to date , four of our facilities have been given a tier 4 rating . facilities receiving a tier 4 rating are required to complete site security plans and possible physical security enhancements . we do not expect the site security plans and possible security enhancements cost will have a material impact on our results of operations , financial position or cash flows . pipeline security - the united states department of homeland security 2019s transportation security administration and the dot have completed a review and inspection of our 201ccritical facilities 201d and identified no material security issues . also , the transportation security administration has released new pipeline security guidelines that include broader definitions for the determination of pipeline 201ccritical facilities . 201d we have reviewed our pipeline facilities according to the new guideline requirements , and there have been no material changes required to date . environmental footprint - our environmental and climate change strategy focuses on taking steps to minimize the impact of our operations on the environment . these strategies include : ( i ) developing and maintaining an accurate greenhouse gas emissions inventory according to current rules issued by the epa ; ( ii ) improving the efficiency of our various pipelines , natural gas processing facilities and natural gas liquids fractionation facilities ; ( iii ) following developing technologies for emission control and the capture of carbon dioxide to keep it from reaching the atmosphere ; and ( iv ) utilizing practices to reduce the loss of methane from our facilities . we participate in the epa 2019s natural gas star program to voluntarily reduce methane emissions . we continue to focus on maintaining low rates of lost-and-unaccounted-for natural gas through expanded implementation of best practices to limit the release of natural gas during pipeline and facility maintenance and operations . employees we employed 4859 people at january 31 , 2013 , including 705 people at kansas gas service who are subject to collective bargaining agreements . the following table sets forth our contracts with collective bargaining units at january 31 , 2013: .
what percentage of employees are subject to collective bargaining agreements?
.