levels must levels naturally levels need levels never levels normal levels now levels of ability levels of abstraction levels of access levels of accuracy levels of achievement levels of action levels of active levels of activity levels of administration levels of aid levels of air levels of air pollution levels of alcohol levels of ammonia levels of analysis levels of antibodies levels of antioxidants levels of anxiety levels of arsenic levels of assistance levels of authority levels of automation levels of autonomy levels of awareness levels of bacteria levels of bilirubin levels of biodiversity levels of blood levels of body levels of brightness levels of business levels of caffeine levels of calcium levels of carbon levels of carbon dioxide levels of care levels of certain levels of certification levels of child levels of cholesterol levels of circulating levels of comfort levels of commitment levels of communication levels of compensation levels of competence levels of competition levels of complexity levels of compliance levels of concentration levels of confidence levels of consciousness levels of consumption levels of contaminants levels of contamination levels of control levels of cooperation levels of copper levels of corruption levels of cortisol levels of courts levels of cover levels of coverage levels of creatinine levels of crime levels of customer levels of customer satisfaction levels of data levels of debt levels of decision levels of decision-making levels of depression levels of destruction levels of detail levels of development levels of different levels of difficulty levels of dopamine levels of economic levels of economic development levels of education levels of education and training levels of educational attainment levels of efficiency levels of emotional levels of employee levels of employment levels of encryption levels of energy levels of engagement levels of english levels of environmental levels of estrogen